Liquid crystal display panel and liquid crystal display device incorporating the same

ABSTRACT

A liquid crystal display panel and a liquid crystal display device incorporating the same are provided. The liquid crystal display panel includes a first substrate, a second substrate and a liquid crystal layer. The first substrate includes a first base, a dielectric layer and a storage capacitor. The storage capacitor includes a reflective electrode. The dielectric layer covers at least part of the storage capacitor. The second substrate is substantially paralleled to the first substrate. The second substrate includes a second base, a black matrix and a common electrode. The black matrix corresponds to the storage capacitor. The black matrix includes an opening corresponding to the reflective electrode. The opening is provided to let an outside light enter into the liquid crystal display panel such that the reflective electrode reflects the outside light to provide a light source to the liquid crystal display panel.

This application claims the benefit of Taiwan application Serial No.95102114, filed Jan. 18, 2006, the subject matter of which isincorporated herein by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The invention relates in general to a liquid crystal display panel and aliquid crystal display device incorporating the same, and moreparticularly to a liquid crystal display panel using an electrode of astorage capacitor as a reflective electrode and forming an openingcorresponding to the storage capacitor on a black matrix and a liquidcrystal display device incorporating the same.

2. Description of the Related Art

Micro-reflective liquid crystal display device is a trans-reflectiveliquid crystal display device capable of forming a micro-reflectiveelement on an ordinary transmissive display panel without employingextra manufacturing process to resolve information recognition failurewhich is caused by strong reflection on the surface when the panel isexposed under the sunshine. However, the original TN mode manufacturingmethod is used without adding any extra manufacturing process. Thestructure of the backlight module or the polarizer is improved toachieve micro-reflection effect. However, during reflection, thereflective liquid crystal display device does not optimize the reflectedvoltage and reflectance (V-R) relationship curve. Moreover, since the TNmode is adopted, the contrast of the liquid crystal display device cannot be improved, largely affecting the practicality of the liquidcrystal display device.

SUMMARY OF THE INVENTION

It is therefore an object of the invention to provide a liquid crystaldisplay panel and a liquid crystal display device incorporating thesame. The liquid crystal display panel uses an electrode of a storagecapacitor as a reflection area and has an opening on an opaque layer(such as a black matrix). The opening corresponds to the reflectionarea, such that the light reflected inwardly, that is, the light L1, ismodulated. Besides, the liquid crystal display panel according to thepresent embodiment of the invention has a dielectric layer on thetopmost of the storage capacitor for dividing the voltage of the liquidcrystal layer in the reflection area to achieve the same saturationvoltage as that in the transmissive area. Since a small part of thereflection area has both the transparent electrode and the reflectiveelectrode, the threshold voltage of the reflection area will be close tothe threshold voltage of the transmissive area, hence achieving higherreflection contrast.

The invention achieves the above-identified object by providing a liquidcrystal display panel including a first substrate, a second substrateand a liquid crystal layer. The first substrate includes a first base, astorage capacitor and a dielectric layer. The storage capacitor isdisposed on the first base and has a reflective electrode. Thedielectric layer is disposed over the first base and covers at leastpart of the storage capacitor. The second substrate is substantiallyparallel to the first substrate and includes a second base, a blackmatrix and a common electrode. The black matrix is disposed on thesecond base and corresponds to the storage capacitor. The black matrixhas an opening. The opening corresponds to the reflective electrode forletting an outside light enter the liquid crystal display panel suchthat the reflective electrode reflects the outside light to provide alight source to the liquid crystal display panel. The common electrodeis disposed on the second base and covers the black matrix and theopening. The liquid crystal layer is disposed between the firstsubstrate and the second substrate.

The invention further achieves the above-identified object by providinga liquid crystal display device including a liquid crystal display panela backlight module, a first polarizer and a second polarizer. The liquidcrystal display panel includes a first substrate, a second substrate anda liquid crystal layer. The first substrate includes a first base, astorage capacitor, a dielectric layer and a transparent electrode. Thestorage capacitor is disposed on the first base and has a reflectiveelectrode. The dielectric layer is disposed over the first base andcovers at least part of the storage capacitor. The dielectric layer hasa contact hole. The transparent electrode is disposed on at least partof the dielectric layer. One end of the transparent electrode iselectrically connected to the reflective electrode via the contact hole.The second substrate is substantially parallel to the first substrateand includes a second base, a black matrix and a common electrode. Theblack matrix is disposed on the second base and corresponds to thestorage capacitor. The black matrix has an opening. The openingcorresponds to the reflective electrode and the end of the transparentelectrode electrically connected to the reflective electrode. Wherebyoutside light enters the liquid crystal display panel such that thereflective electrode reflects the outside light to provide a lightsource to the liquid crystal display panel. The common electrode isdisposed on the second base and covers the black matrix and the opening.The liquid crystal layer is disposed between the first substrate and thesecond substrate. The backlight module is disposed underneath the liquidcrystal display panel. The first polarizer is disposed between thebacklight module and the liquid crystal display panel. The secondpolarizer is disposed on the liquid crystal display panel.

The invention further achieves the above-identified object by providinga liquid crystal display panel including a first substrate, a secondsubstrate and a liquid crystal layer. The first substrate includes afirst base, a storage capacitor and a dielectric layer. The storagecapacitor is disposed on the first base and has a reflective electrode.The dielectric layer is disposed over the first base and covers at leastpart of the storage capacitor. The second substrate is substantiallyparallel to the first substrate and includes a second base, a colorfilter and a common electrode. The color filter is disposed on thesecond base. The common electrode is disposed on the color filter. Theliquid crystal layer is disposed between the first substrate and thesecond substrate.

Other objects, features, and advantages of the invention will becomeapparent from the following detailed description of the preferred butnon-limiting embodiments. The following description is made withreference to the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1A is a structural cross-sectional view of a first type of liquidcrystal display device according to a preferred embodiment of theinvention;

FIG. 1B is a structural cross-sectional view of a second type of liquidcrystal display device according to a preferred embodiment of theinvention;

FIG. 1C is a structural cross-sectional view of a third type of liquidcrystal display device according to a preferred embodiment of theinvention;

FIG. 1D is a structural cross-sectional view of a fourth type of liquidcrystal display device according to a preferred embodiment of theinvention;

FIG. 2 illustrates voltage and reflectance (V-R) relationship curves ina reflection area of a liquid crystal display panel and a voltage andtransmittance (V-T) relationship curve in a transmissive area of aliquid crystal display panel when the transparent electrode is notwithin the reflection area according to a preferred embodiment of theinvention; and

FIG. 3 illustrates voltage and reflectance (V-R) relationship curves ina reflection area of a liquid crystal display panel and a voltage andtransmittance (V-T) relationship curve in a transmissive area of aliquid crystal display panel when a small part of the transparentelectrode 34 is within the reflection area according to a preferredembodiment of the invention.

DETAILED DESCRIPTION OF THE INVENTION

Referring to FIG. 1A, a structural cross-sectional view of a first typeof liquid crystal display device according to a preferred embodiment ofthe invention is shown. As shown in FIG. 1A, the liquid crystal displaydevice 10 is includes a liquid crystal display panel 20, a backlightmodule 60, a first polarizer 70 and a second polarizer 80. The liquidcrystal display panel 20 includes a first substrate 30, a secondsubstrate 40 and a liquid crystal layer 50. The first substrate 30includes a first base 31, a storage capacitor 32, a dielectric layer 33and a transparent electrode 34. The storage capacitor 32 is disposed onthe first base 31 and has a reflective electrode 32 a. The dielectriclayer 33 is disposed over the first base 31 and covers at least part ofthe storage capacitor 32. The dielectric layer 33 has a contact hole 33a. The transparent electrode 34 is disposed on at least part of thedielectric layer 33. One end of the transparent electrode 34 iselectrically connected to the reflective electrode 32 a via the contacthole 33 a. The second substrate 40 is substantially parallel to thefirst substrate 30 and includes a second base 41, a black matrix 42 anda common electrode 44. The black matrix 42 is disposed on the secondbase 41 and corresponds to the storage capacitor 32. The black matrix 42has an opening 42 a. The black matrix 42 may comprise other opaquelayers. The opening 42 a corresponds to the reflective electrode 32 aand the end of the transparent electrode 34 electrically connected tothe reflective electrode 32 a. The opening 42 a disposed above thestorage capacitor 32 is provided to let outside light L1 enter theliquid crystal display panel 20 such that the reflective electrode 32 areflects the outside light to provide a light source to the liquidcrystal display panel 20. The common electrode 44 is disposed on thesecond base 41 and covers the black matrix 42 and the opening 42 a. Theliquid crystal layer 50 is disposed between the first substrate 30 andthe second substrate 40. The backlight module 60 is disposed underneaththe liquid crystal display panel 20 and adjacent to the first substrate31 to provide inside light L2 to the liquid crystal display panel 20.The first polarizer 70 is disposed between the backlight module 60 andthe liquid crystal display panel 20. The second polarizer 80 is disposedon the liquid crystal display panel 20 and adjacent to the secondsubstrate 40. The contact hole 33 a is disposed within the projectionarea of the opening 42 a, or, part of the contact hole 33 a is disposedwithin the projection area of the opening 42 a.

Besides, the liquid crystal display panel 20 further includes a firstvertical alignment film 35 and a second vertical alignment film 45. Thefirst vertical alignment film 35 is disposed on dielectric layer 33 andcovers the transparent electrode 34 and the storage capacitor 32. Thesecond vertical alignment film 45 is disposed on the common electrode44. The liquid crystal layer 50 is disposed between the first verticalalignment film 35 and the second vertical alignment film 45.

In the present embodiment of the invention, the second substrate 41further includes a color filter 43. The color filter 43 is disposedbetween the second base 41 and the common electrode 44, and covers theblack matrix 42 and the opening 42 a.

However, the color filter of the liquid crystal display panel can bedesigned to have an opening. Referring to FIG. 1B, a structuralcross-sectional view of a second type of liquid crystal display device10 a according to a preferred embodiment of the invention is shown. Asshown in the liquid crystal display device 10 a, the second substrate 40a of the liquid crystal display panel 20 a further includes a colorfilter 43 a and a flat layer 46. The color filter 43 a is disposedbetween the second base 41 and the common electrode 44, and covers theblack matrix 42. The color filter 43 a has another opening 43 bcorresponding to the opening 42 a of the black matrix 42. The flat layer46 is disposed between the color filter 43 a and the common electrode44, and covers the opening 42 a of the black matrix 42 and the opening43 b of the color filter 43 a.

Furthermore, the storage capacitor of the liquid crystal display paneldoes not require the opening of the black matrix. Referring to FIG. 1C,a structural cross-sectional view of a third type of liquid crystaldisplay device 10 b according to a preferred embodiment of the inventionis shown. As shown in the liquid crystal display device 10 b, the secondsubstrate 40 b of the liquid crystal display panel 20 b further includesa color filter 43 c disposed on the second base 41. The common electrode44 is disposed on the color filter 43 c.

The storage capacitor of the liquid crystal display panel does notrequire the opening of the black matrix. The color filter can bedesigned to have an opening. Referring to FIG. 1D, a structuralcross-sectional view of a fourth type of liquid crystal display device10 c according to a preferred embodiment of the invention is shown. Asshown in the liquid crystal display device 10 c, the second substrate 40c of the liquid crystal display panel 20 c further includes a colorfilter 43 d and a flat layer 46 a. The color filter 43 d has an opening43 e corresponding to the reflective electrode 32 a and the end of thetransparent electrode 34 electrically connected to the reflectiveelectrode 32 a. The flat layer 46 a is disposed between the color filter43 d and the common electrode 44, and covers the opening 43 e.

Moreover, the liquid crystal display panels 20˜20 c can respectively bea vertical alignment (VA) type of liquid crystal display panel or amicro-reflection type display panel. Each liquid crystal layer 20˜20 cincludes a number of vertically aligned liquid crystal molecules.Moreover, the liquid crystal display panels 20˜20 c form a reflectionarea corresponding to the storage capacitor 32, respectively. The liquidcrystal display panels 20˜20 c form a transmissive area corresponding tothe transparent electrode 34, respectively. When a voltage is applied tothe transparent electrode 34, the dielectric layer 33 is provided todivide the voltage in the reflection area of the liquid crystal layersuch that the voltage and reflectance (V-R) relationship curve of theliquid crystal display panels 20˜20 c on the reflective electrode 32 ais substantially matched to the voltage and transmittance (V-T)relationship curve on the transparent electrode 34 of the liquid crystaldisplay panels 20˜20 c. That is, through the design of the dielectriclayer 33, the voltage and reflectance (V-R) relationship curve in thereflection area of the liquid crystal display panels 20˜20 c will besubstantially matched to the voltage and transmittance (V-T)relationship curve in the transmissive area of the liquid crystaldisplay panels 20˜20 c, largely increasing the contrast of the liquidcrystal display devices 10˜10 c.

Referring to FIG. 2, voltage and reflectance (V-R) relationship curvesin a reflection area of a liquid crystal display panel and a voltage andtransmittance (V-T) relationship curve in a transmissive area of aliquid crystal display panel when the transparent electrode is notwithin the reflection area according to a preferred embodiment of theinvention are shown. As shown in FIG. 2, when the thickness of thedielectric layer 33 is different, for example, when the thickness h2 islarger than the thickness h1, the matching between the voltage andreflectance (V-R) relationship curve and the voltage and transmittance(V-T) relationship curve will be different accordingly. However, whenthe thickness of the dielectric layer 33 is too thick or too thin, thevoltage and reflectance (V-R) relationship curve will not match with thevoltage and transmittance (V-T) relationship curve. When the dielectriclayer has a thickness ranging from about 0.6 μm to about 5 μm, thevoltage and reflectance (V-R) relationship curve matches well with thevoltage and transmittance (V-T) relationship curve.

Referring to FIG. 3, voltage and reflectance (V-R) relationship curvesin a reflection area of a liquid crystal display panel and a voltage andtransmittance (V-T) relationship curve in a transmissive area of aliquid crystal display panel when a small part of the transparentelectrode is within the reflection area according to a preferredembodiment of the invention are shown. As shown in FIG. 3, since a smallpart of the transparent electrode 34 is within the reflection area, andpart of the voltage on the reflection of the liquid crystal layer isprovided by the voltage of the transparent electrode 34, the rising partin the front segment of the voltage and reflectance (V-R) relationshipcurve in the reflection area will be better matched to the rising partin the front segment of the voltage and transmittance (V-T) relationshipcurve in the transmission area. When the thickness of the dielectriclayer 33 is different, for example, when the thickness h5 is larger thanthe thickness h4 and the thickness h4 is larger than the thickness h3,the matching between the voltage and reflectance (V-R) relationshipcurve and the voltage and transmittance (V-T) relationship curve will bedifferent accordingly.

Any one who is skilled in the technology of the present embodiment ofthe invention will understand that the technology of the presentembodiment of the invention is not limited thereto. For example,examples of the dielectric layer 33 include inorganic materials ororganic materials. Besides, the reflective electrode 32 a includes areflective metal, a reflective metallic alloy or any combinationthereof. The reflective electrode 32 a can be a single layered or amultiple layered structure in the sequential order of titanium/aluminumor titanium/aluminum/titanium/aluminum from the bottom layer to the toplayer. Moreover, examples of the first base 31 and the second base 41include a glass substrate, an insulated substrate, a plastic substrate,a ceramic substrate or a flexible substrate. The transparent electrode34 is a pixel electrode inside a pixel of an active matrix pixel array,and the material of the transparent electrode includes a transparentconductive material including indium tin oxide (ITO), indium zinc oxide(IZO), cadmium tin oxide (CTO), stannum dioxide (SnO2), zinc oxide (ZnO)or other similar transparent metallic oxides. The liquid crystal displaydevice 10 can be applied to any electronic devices requiring a displayunit. Examples of the electronic device include computer screen, flatTV, monitor screen, mobile phone, handheld game device, digital camera(DC), digital video (DV), digital audio device, personal digitalassistant (PDA), notebook and table PC.

According to the liquid crystal display panel and the liquid crystaldisplay device disclosed in the above embodiment of the invention, theliquid crystal display panel uses an electrode of a storage capacitor asa reflection area and has an opening on an opaque layer (such as a blackmatrix) corresponding to the reflection area, such that the lightreflected inwardly, that is, the light L1, is modulated. Besides, theliquid crystal display panel according to the present embodiment of theinvention has a dielectric layer on the topmost of the storage capacitorfor dividing the voltage of the liquid crystal layer in the reflectionarea to achieve the same saturation voltage as that in the transmissivearea. Since a small part of the reflection area has both the transparentelectrode and the reflective electrode, the threshold voltage of thereflection area will be close to the threshold voltage of thetransmissive area, hence achieving higher reflection contrast.

While the invention has been described by way of example and in terms ofa preferred embodiment, it is to be understood that the invention is notlimited thereto. On the contrary, it is intended to cover variousmodifications and similar arrangements and procedures, and the scope ofthe appended claims therefore should be accorded the broadestinterpretation so as to encompass all such modifications and similararrangements and procedures.

1. A liquid crystal display panel, comprising: a first substrate,comprising: a first base; a storage capacitor disposed on the first baseand having a reflective electrode; and a dielectric layer disposed overthe first base and covering at least part of the storage capacitor; asecond substrate substantially parallel to the first substrate,comprising: a second base; an opaque layer disposed on the second baseand corresponding to the storage capacitor, wherein the opaque layer hasa first opening corresponding to the reflective electrode, the firstopening being located over the storage capacitor; a common electrodedisposed on the second base and covering the opaque layer and the firstopening; a color filter disposed between the second base and the commonelectrode and covering the opaque layer, wherein the color filter has asecond opening corresponding to the first opening, the second openingbeing located over the storage capacitor; and a flat layer disposedbetween the color filter and the common electrode, and covering thefirst opening and the second opening; and a liquid crystal layerdisposed between the first substrate and the second substrate.
 2. Theliquid crystal display panel according to claim 1, wherein thedielectric layer has a contact hole, the first substrate furthercomprises a transparent electrode disposed on at least part of thedielectric layer, and one end of the transparent electrode iselectrically connected to the reflective electrode via the contact hole.3. The liquid crystal display panel according to claim 2, furthercomprising: a first vertical alignment film disposed on the dielectriclayer and covering the transparent electrode; and a second verticalalignment film disposed on the common electrode; wherein the liquidcrystal layer is disposed between the first vertical alignment film andthe second vertical alignment film.
 4. The liquid crystal display panelaccording to claim 2, wherein the dielectric layer divides the voltagein a reflection area of the liquid crystal layer such that the voltageand reflectance (V-R) relationship curve on the reflective electrode issubstantially matched to the voltage and transmittance (V-T)relationship curve on the transparent electrode when a voltage isapplied to the transparent electrode.
 5. The liquid crystal displaypanel according to claim 1, wherein the first opening passes through theopaque layer and the second opening passes through the color filter. 6.The liquid crystal display panel according to claim 1, wherein theliquid crystal layer includes vertically aligned liquid crystalmolecules.
 7. The liquid crystal display panel according to claim 1,wherein the dielectric layer has a thickness ranging from about 0.6 μmto about 5 μm.
 8. The liquid crystal display panel according to claim 1,wherein the opaque layer is a black matrix.
 9. The liquid crystaldisplay panel according to claim 1, wherein the reflective electrodecomprises a reflective metal, a reflective metallic alloy or acombination thereof.
 10. The liquid crystal display panel according toclaim 1, wherein the reflective electrode comprises titanium/aluminum ortitanium/aluminum/titanium/aluminum.
 11. A liquid crystal displaydevice, comprising: a liquid crystal display panel, comprising: a firstsubstrate including: a first base; a storage capacitor disposed on thefirst base and having a reflective electrode; a dielectric layerdisposed over the first base and covering at least part of the storagecapacitor, wherein the dielectric layer has a contact hole; and atransparent electrode disposed on at least part of the dielectric layer,wherein one end of the transparent electrode is electrically connectedto the reflective electrode via the contact hole; a second substratesubstantially parallel to the first substrate and including: a secondbase; a black matrix disposed on the second base and corresponding tothe storage capacitor, wherein the black matrix has a first openingcorresponding to the reflective electrode, whereby outside light entersthe liquid crystal display panel such that the reflective electrodereflects the outside light to provide a light source to the liquidcrystal display panel, the first opening being located over the storagecapacitor; a common electrode disposed on the second base and coveringthe black matrix and the first opening; a color filter disposed betweenthe second base and the common electrode and covering the black matrix,wherein the color filter has a second opening corresponding to the firstopening, the second opening being located over the storage capacitor;and a flat layer disposed between the color filter and the commonelectrode and covering the first opening and the second opening; and aliquid crystal layer disposed between the first substrate and the secondsubstrate; a backlight module disposed underneath the liquid crystaldisplay panel; a first polarizer disposed between the backlight moduleand the liquid crystal display panel; and a second polarizer disposed onthe liquid crystal display panel.
 12. The liquid crystal display deviceaccording to claim 11, wherein the first opening passes through theopaque layer and the second opening passes through the color filter. 13.The liquid crystal display device according to claim 11, furthercomprising: a first vertical alignment film disposed on the dielectriclayer and covering the transparent electrode; and a second verticalalignment film disposed on the common electrode; wherein the liquidcrystal layer is disposed between the first vertical alignment film andthe second vertical alignment film.
 14. The liquid crystal displaydevice according to claim 11, wherein the dielectric layer has athickness ranging from about 0.6 μm to about 5 μm.
 15. The liquidcrystal display device according to claim 11, wherein the dielectriclayer divides the voltage in a reflection area of the liquid crystallayer such that the voltage and reflectance (V-R) relationship curve onthe reflective electrode is substantially matched to the voltage andtransmittance (V-T) relationship curve on the transparent electrode whena voltage is applied to the transparent electrode.
 16. The liquidcrystal display device according to claim 11, wherein the reflectiveelectrode comprises a reflective metal, a reflective metallic alloy or acombination thereof.
 17. The liquid crystal display device according toclaim 11, wherein the reflective electrode comprises titanium/aluminumor titanium/aluminum/titanium/aluminum.
 18. The liquid crystal displaydevice according to claim 11, wherein the liquid crystal display panelis a vertical alignment (VA) type of liquid crystal display panel.